JP3200289B2 - Lithium secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithium secondary battery having a high capacity negative electrode.

[0002]

2. Description of the Related Art With the miniaturization and power saving of electronic devices,
A secondary battery using an alkali metal such as lithium has attracted attention. When an alkali metal such as lithium is used alone for the negative electrode, dendrite (dendritic crystals) is generated and grown on the metal dissolution-precipitation surface by repeated charge and discharge, ie, the dissolution-precipitation process of the alkali metal. There is a problem that a short circuit inside the battery is induced by penetrating the separator and connecting to the positive electrode. It has been found that when an alkali metal alloy is used for a negative electrode for a secondary battery instead of an alkali metal, the generation of dendrites is suppressed and the charge / discharge cycle characteristics are improved as compared with the case of using an alkali metal alone. However, even if an alkali metal alloy is used, generation of dendrites does not completely disappear, and a short circuit inside the battery due to generation of dendrites may occur.
In recent years, instead of using a dissolution-precipitation process of a metal such as an alkali metal or an alloy thereof, or a dissolution-precipitation-diffusion process in a solid, a carbon using an absorption-release process of an alkali metal ion has been developed. Organic materials such as conductive polymers have been developed. As a result, generation of dendrite generated when an alkali metal or an alloy thereof is used does not occur in principle, and the problem of a short circuit inside the battery has been drastically reduced.

When carbon is used as a negative electrode active material, the amount of lithium inserted between carbon layers is 1 lithium atom per 6 carbon atoms, that is, C ₆ Li, and the unit of carbon at that time is The capacity per weight is 372 mAh / g. Carbon has a wide range of structures from what is called amorphous carbon to graphite, and the size and arrangement of carbon hexagonal planes vary depending on starting materials, production methods, and the like. Examples of carbon materials conventionally used as negative electrode active materials include, for example, JP-A-62-90863 and JP-A-62-1.
No. 22066, JP-A-63-213267,
JP-A-1-204361, JP-A-2-82466
JP, JP-A-3-25253, JP-A-3-2
No. 85273, Japanese Unexamined Patent Publication No. 3-289068, and the like. However, none of these carbons reach the above-mentioned theoretical capacity. The potential of Li / Li ⁺ at the time of deintercalation rises linearly, and does not show a sufficient capacity in a potential range that can be used when actually constructing a battery system. A negative electrode having a satisfactory capacity cannot be produced. Also, when creating the negative electrode, it is necessary to consider the true density of the carbon material, and when aiming for high capacity in a limited volume such as a battery system, the packing density per unit volume, that is, the bulk density is important. Factors. The bulk density governs the shape and size of the carbon particles.
Among the examples of -90863, none of the fibrous carbons disclosed in JP-A-2-82466, JP-A-3-285273, and JP-A-3-289068 satisfy the above-mentioned theoretical capacity, and are satisfactory in producing a battery. A negative electrode having a large negative electrode capacity cannot be manufactured. In addition, Japanese Unexamined Patent Publication
Pyrolytic carbon produced by a gas phase method as shown in 3-24555 shows high charge / discharge stability, but it is difficult to produce a thick-film electrode and to obtain a high-capacity electrode by this production method. .

Similarly, Japanese Patent Application Laid-Open Nos. 4-112455 and 4-1154 disclose that a graphite material is used as a negative electrode active material.
57, JP-A-4-115458, JP-A-4-23797
1, Japanese Patent Application Laid-Open No. 5-28996, etc., does not reach the above-mentioned theoretical capacity, and it is not possible to produce a negative electrode having a satisfactory negative electrode capacity for producing a battery.

JP-A-3-216960, JP-A-4-39
864, respectively, can form an alloy with a composite negative electrode of porous carbon absorbing lithium and lithium formed so as not to block pores on its surface, and an alkali metal as an active material inside pores of the carbonaceous material. A negative electrode has been disclosed in which a support is formed by impregnating a metal, and an alkali metal is supported on the support. Also, Japanese Patent Application Laid-Open No.
No. 3 discloses a non-aqueous electrolyte battery having a carbon electrode formed by sintering a carbon material having a film formed of a highly conductive metal in order to improve current collection.

[0006]

However, as described above, the theoretical capacity (372 mAh / g) can also be obtained by using various carbon materials and graphite materials for the negative electrode active material.
Therefore, a negative electrode having a satisfactory negative electrode capacity in producing a battery cannot be produced.

Japanese Patent Application Laid-Open No. HEI 3-216960 discloses a composite negative electrode of porous carbon having occluded lithium and lithium formed on the surface thereof so as not to block pores.
In a negative electrode in which a metal capable of forming an alloy with an alkali metal as an active material is impregnated inside pores of a carbonaceous material of 9864, and a negative electrode in which an alkali metal is supported, an active material of these electrodes is used. Is lithium (alkali metal)
In the electrode, an alkali compound or an alkali metal is synthesized, and there is a problem that generation of dendrite, which is a disadvantage when an alkali metal is used for a negative electrode, is not completely eliminated. In the non-aqueous electrolyte battery having a carbon electrode formed by sintering a carbon material coated with a highly conductive metal as disclosed in JP-A-4-184863, the current that can be taken out is not so large, and a negative electrode having a satisfactory negative electrode capacity is produced. There is a problem that you can not.

A negative electrode obtained by mixing graphite and copper oxide as disclosed in Japanese Patent Application No. 5-112835, and a graphite-copper oxide composite prepared by subjecting graphite of Japanese Patent Application No. 5-136099 to copper plating and oxidation are used. Although there is a negative electrode, etc., if an electrode that is simply mixed with copper oxide is used, not all of the mixed copper oxide is involved in the reaction, and copper oxide composite graphite obtained by oxidizing copper-plated graphite When using materials,
There is a problem that the manufacturing process becomes complicated.

In view of these problems, the present invention provides a high-capacity and high-capacity electrode by providing copper oxide in contact with graphite capable of intercalating and deintercalating lithium and providing a mixed electrode with a binder. An object of the present invention is to provide a composite graphite negative electrode that can reduce the number of steps in electrode production, and a high-voltage lithium secondary battery that has a high capacity by imparting a reversal prevention capacity.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the negative electrode of the lithium secondary battery of the present invention has a structure in which all or a part of the graphite particles capable of intercalating / deintercalating lithium are used. After chemically producing (depositing) copper oxide mainly on the top, using a composite produced by a production method of producing a contact pair of particles in a liquid, and mixing this with a binder It is made. At this time, an integrated product of the negative electrode and the negative electrode current collector can also be manufactured.

The graphite used as the main component of the negative electrode active material used in the present invention has an average spacing (d ₀₀₂ ) of (002) planes by a wide angle X-ray diffraction method of 0.335 to 0.340 nm,
The crystallite thickness (Lc) in the (002) plane direction is 10 nm or more, and the crystallite thickness (La) in the (110) plane direction is 10 nm.
The above materials are used, and a high-capacity electrode can be obtained by using these materials. Factors affecting the capacity and charge / discharge potential include physical properties related to the layered structure of carbon. Physical properties related to the layered structure of carbon include (00
2) The plane spacing (d ₀₀₂ ) of the planes, that is, the interlayer distance and the crystallite size. Since the potential at the time of deintercalation of lithium becomes closer to the potential of lithium by increasing the degree of crystallinity, it is possible to expect to obtain a higher capacity carbon body electrode. Therefore, when considering the battery capacity that can be used when assembled as a lithium secondary battery, the crystallinity is poor when the crystallite thickness (Lc) in the (002) plane direction by X-ray wide-angle diffraction is 10 nm or less. Therefore, the battery capacity that can be used when assembled as a lithium secondary battery becomes small, which is not practical. Also,
The crystallite thickness (La) in the (110) plane direction is 1
When the thickness is less than 0 nm, the crystallinity is poor, so that the battery capacity that can be used when assembled as a lithium secondary battery becomes small, which is not practical.

[0012] Graphite as a main component of the negative electrode active material used in the present invention was prepared using argon laser Raman.
580 cm ^-1 around 1360 cm ^-1 vicinity of the peak intensity ratio of the relative peak of, i.e. R value is preferably 0.4 or less. If it is larger than 0.4, the crystallinity will be low, and the potential at the time of deintercalation of lithium will be higher than the potential of lithium. Therefore, when assembled as a lithium secondary battery, the usable battery capacity is small. Is not practical.

[0013] The graphite which can be used is not limited as long as it satisfies the above-mentioned physical property conditions. For example, artificial graphite obtained from easily graphitizable carbon such as natural graphite, quiche graphite, petroleum coke or coal pitch coke; Alternatively, graphites such as expanded graphite can be used. The shape of the graphite particles may be spherical, flaky, fibrous, or any of their pulverized products.
A scaly shape or a crushed product thereof is preferred.

When graphite is used as the negative electrode, the graphite preferably has a particle size of 80 μm or less. The particle size is a value obtained as a particle size having a peak (modal size in volume-based measurement) in a particle size distribution obtained by volume-based particle size distribution measurement. When graphite having a particle size of more than 80 μm is used, the contact area with the electrolyte becomes small, so that phenomena such as diffusion of lithium in the particles and a decrease in the density of reaction sites occur. Problems arise.

A method for producing a composite in contact with copper oxide on the surface of graphite particles, ie, strictly speaking, a copper oxide in which the copper oxide contacts the graphite particles on at least a part of the surface of the graphite particles Alternatively, a method for producing copper hydroxide is as follows.

Coprecipitation method Graphite powder and a copper salt, for example, copper sulfate, are mixed, and water is added to dissolve the copper sulfate so that the molar ratio is twice or more the amount of copper ions present therein. A method in which an excess of an alkaline compound is added as an aqueous solution or a solid, left at a temperature of room temperature (20 ° C.) or higher, preferably 60 ° C. or higher, further left at room temperature, and then suction-filtered,
Starting materials are copper salts.

Evaporation (decomposition) method A high-temperature decomposable copper compound such as copper acetate is kept under a high vacuum to utilize heat evaporation or decomposition.

Thermal decomposition method A volatile copper compound is mixed with graphite and heated in an oxidizing atmosphere such as in the presence of air or oxygen to decompose the copper compound.

As described above, various methods can be used, but the present invention is not limited to these methods. Of these, the coprecipitation method is preferred in terms of cost and workability. Generally, copper hydroxide is said to be a gel of copper oxide hydrate. If copper hydroxide is partially generated, a dehydration treatment is performed later.

As a method of performing the dehydration treatment after the above-described copper hydroxide is formed, it is necessary to perform the dehydration treatment in an oxidizing atmosphere which is advantageous for forming copper oxide. Therefore, a gaseous oxidizing agent such as air, oxygen, Drying and dehydration using ozone, etc.
Liquid oxidants, such as hydrogen peroxide, water with dissolved oxygen,
A method of dehydration and washing with oxidizing using oxo acid (nitric acid, permanganic acid, chromic acid, dichromic acid, chloric acid, hypochlorous acid, etc.), dehydrating in an oxidizing atmosphere under hot water However, the present invention is not limited thereto.

In the above-mentioned dehydration treatment using a gas such as air or oxygen, the treatment should be performed at a temperature lower than the combustion temperature of graphite. The combustion temperature of graphite varies depending on the type of graphite, but is about 600 ° C. or higher. Therefore, 600
It is preferable to carry out at a temperature of not more than ° C. In addition, in the dehydration treatment under an oxidizing atmosphere using air at 600 ° C. or lower, the graphite surface is oxidized and the carboxyl group varies depending on the type of graphite, oxidation time, oxygen partial pressure, ratio of graphite to copper, etc.
Functional groups such as lactone, hydroxyl group and carbonyl group are generated. Therefore, it is more preferable to perform the dehydration treatment at 400 ° C. or lower.

The ratio of graphite to copper oxide constituting the graphite composite with copper oxide varies depending on the type and particle size of graphite or the form of copper oxide deposition, but the weight ratio of graphite to copper oxide is 98%. 0.5: 1.5 to 55:45. More preferably, the ratio is 98.5: 1.5 to 72:28. If the weight ratio of the copper oxide component is less than 98.5, the effect of the attached copper oxide is not remarkably exhibited, and
If the ratio is larger than 5:45, the number of lithium ion reaction sites is reduced during charging and discharging of graphite, and when assembled as a lithium secondary battery, the usable battery capacity is reduced, which is not practical.

The negative electrode is formed by mixing a composite and a binder in contact with copper oxide on the surface of all or a part of the graphite particles shown above. As the binder, a fluorine-based polymer such as polytetrafluoroethylene and polyvinylidene fluoride, a polyolefin-based polymer such as polyethylene and polypropylene, and synthetic rubbers can be used, but are not limited thereto. This mixing ratio is 99: 1 to 70:30 by weight ratio of the composite having the copper oxide adhered on the surface of all or a part of the graphite particles to the binder.
It can be. If the binder is larger than 70:30, the resistance or polarization of the electrode becomes large and the discharge capacity becomes small, so that a practical lithium secondary battery cannot be manufactured. On the other hand, if the binder is less than 99: 1, the battery has only a binding ability that cannot maintain the shape as an electrode, and it is difficult to manufacture a battery due to the occurrence of falling off of the active material and, consequently, a decrease in mechanical strength. become. In the production of the negative electrode, it is preferable to perform a heat treatment at a temperature around the melting point of each binder in order to enhance the binding property.

The particle diameter of the copper oxide to be composited with the graphite of the graphite composite to which the copper oxide is attached is preferably about 1 μm or more from the viewpoint of the manufacturing process derived from the characteristics of the glass filter. It is preferable that the particle diameter is in the range of the particle size or less. The contact state between the graphite particles and the copper oxide particles in the copper oxide-adhered graphite composite of the present application is such that the copper oxide particles that have started to be deposited beside the graphite particles in the mixed state are enlarged while trying to take in carbon, but cannot be taken up. Since the growth stops beforehand, many graphite particles take the form of so-called twin particles in contact with copper oxide particles. The reason why the problem occurs when the particle size of copper oxide is larger than the particle size of graphite that exists at the same time is that the reaction area decreases as the particle size increases, and the effect as copper oxide is relatively small on the characteristics of the electrode reaction. This is because, at the same time, the effect as copper oxide is relatively reduced also in the relative comparison of the electrode reactivity with graphite. Also, from the viewpoint of the adhesive strength between graphite and copper oxide particles, it is more advantageous for copper oxide particles having a relatively large specific gravity to be small, and when the particle size is relatively large compared to graphite, repeated electrode reactions, that is, The frequency of liberation of the copper oxide component as an active material from the electrode surface due to charge and discharge increases, which is one of the causes of deterioration of electrode characteristics. On the other hand, if another separation method and a washing method such as using a glass filter having a small pore diameter are used, and the lower limit of the particle size by the characteristics of the glass filter is eliminated, the particle size of graphite that is present at the same time is simply reduced. It is clear that the range is as follows.

In order to collect current from the negative electrode, a current collector is required. Examples of the current collector include a metal foil, a metal mesh, and a three-dimensional porous body. As the metal used for the current collector,
A metal that is difficult to alloy with lithium is preferable in terms of mechanical strength when charge and discharge cycles are repeated. In particular, iron, nickel, cobalt, copper, titanium, vanadium, chromium, and manganese alone or alloys thereof are preferable.

As the ion conductor, for example, an organic electrolyte, a solid polymer electrolyte, an inorganic solid electrolyte, a molten salt, or the like can be used. Among these, an organic electrolyte is preferably used.
The organic electrolyte is composed of a solvent and a solute, and the electrolyte is adjusted by dissolving the electrolyte in the solvent. As the solvent for the organic electrolyte, propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, esters such as γ-butyrolactone, tetrahydrofuran, substituted tetrahydrofuran such as 2-methyltetrahydrofuran, dioxolane, diethyl ether ,
Ethers such as dimethoxyethane, diethoxyethane, and methoxyethoxyethane; dimethylsulfoxide, sulfolane, methylsulfolane, acetonitrile, methyl formate, methyl acetate, and the like.
Used as a mixed solvent of more than one species. Examples of the electrolyte include lithium salts such as lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium arsenide hexafluoride, lithium trifluoromethanesulfonate, lithium halide, and lithium aluminate. A mixture of two or more types is used. The solvent and the electrolyte used when preparing the electrolyte are not limited to those described above.

As the positive electrode in the lithium secondary battery of the present invention, LiCoO ₂ , LiNiO ₂ and L
_{i x M y N z O 2} ( and a where M is Fe, Co, either Ni, N represents a transition metal, 4B group or 5B group metal,), LiMn ₂ O ₄ and LiMn _2-x An oxide containing lithium such as N _y O ₄ (where N represents a transition metal, a 4B group, or a 5B group metal) is used as a positive electrode active material, and a conductive material, a binder, and in some cases, a solid material. It is formed by mixing an electrolyte and the like. This mixing ratio depends on the active material 1
The conductive material can be 5 to 50 parts by weight and the binder can be 1 to 30 parts by weight with respect to 00 parts by weight. As the conductive material, carbons such as carbon black (acetylene black, thermal black, channel black, etc.), graphite powder, metal powder, and the like can be used, but are not limited thereto. The binder may be a fluorine-based polymer such as polytetrafluoroethylene or polyvinylidene fluoride, a polyolefin-based polymer such as polyethylene or polypropylene, or a synthetic rubber, but is not limited thereto. If the conductive material is less than 5 parts by weight or the binder is more than 30 parts by weight, the resistance or polarization of the electrode increases and the discharge capacity decreases, so that a practical lithium secondary battery cannot be manufactured. When the amount of the conductive material is more than 50 parts by weight (parts by weight vary depending on the type of the conductive material to be mixed), the amount of the active material contained in the electrode decreases, so that the discharge capacity as the positive electrode decreases. When the binder is smaller than 1 part by weight, the binding ability is lost. When the binder is larger than 30 parts by weight, as in the case of the conductive material,
This is not practical because the amount of active material contained in the electrode decreases, and as described above, the resistance or polarization of the electrode increases and the discharge capacity decreases. In producing the positive electrode, it is preferable to perform a heat treatment at a temperature around the melting point of each binder in order to improve the binding property.

[0028]

The negative electrode according to the present invention is an electrode obtained by mixing a binder and a composite in which copper oxide is in contact with all or part of the graphite particles capable of intercalating / deintercalating lithium. There is high capacity. This is because the reversibly changing composite oxide of lithium and copper was formed in the electrochemically reduced copper oxide.

In addition, by the composite treatment of copper oxide and graphite,
Since it takes the form of twin particles, the contact property is high, the resistance component associated with the contact between the particles is reduced, and the electrode reactivity of copper oxide is improved accordingly.

When the production method of the graphite-copper oxide composite is compared, as shown in FIG. 1 (a), in the plating method, the surface of the powdered carbon (graphite) is treated with a pretreatment liquid in order to perform the powder wet plating method. Activated, immersed in plating solution, activated to form a uniform film and rinsed with water as post-treatment,
It is indispensable that it takes time because the process is used. On the other hand, in the present invention, as shown in FIG. 1 (b), heat treatment and water washing / oxidation treatment are simply performed after mixing, so that the number of steps is reduced and the size of the apparatus, particularly the size of the reaction tank, can be reduced. There are benefits.

Therefore, the lithium secondary battery using the negative electrode according to the present invention can reduce the number of steps in manufacturing the electrode, and can provide an excellent lithium secondary battery having a high capacity.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.

A method for measuring the crystallite size (Lc, La) by the X-ray wide-angle diffraction method is a known method, for example, "Carbon Materials Experimental Techniques 1 p55-63, edited by the Society of Carbon Materials (Science and Technology Corporation)". And the method described in JP-A-61-111907. Further, 0.9 was used as the shape factor K for obtaining the size of the crystallite. The particle size was measured using a laser diffraction type particle size distribution meter, and determined as a particle size having a peak in the particle size distribution (modal size in volume-based measurement).

Example 1 Preparation of Graphite Composite with Copper Oxide Attached to graphite particles of a composite having copper oxide adhered on the surface of all or a part of graphite particles used as a negative electrode active material, natural graphite (scale-like) made in Madagascar was used. , Particle size 11 μm, d ₀₀₂
Is 0.337 nm, Lc is 27 nm, La is 17 nm,
The R value was 0 and the specific surface area was 8 m ² / g), and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, 120 parts by weight of the above graphite powder and 97 parts by weight of copper sulfate pentahydrate (CuSO ₄ .5H ₂ O) (molar ratio: 100: 3.88) are measured and mixed well in a beaker. Lithium hydroxide (LiOH.H ₂ O) 16
Add 3 parts by weight (10 times the molar ratio to Cu ²⁺ ), mix well, add 1000 ml of ion-exchanged water, stir, add C
After uSO ₄ · 5H ₂ O and LiOH · H ₂ O is dissolved, 9
Heat for 20 hours on a hot plate maintained at 0 ° C. Replenish ion-exchanged water as needed with evaporation. afterwards,
After heating was completed and left at room temperature (about 20 ° C.) for 12 hours, the solution was suction-filtered with a glass separator filter paper (pore size: 1 μm), washed with water until the filtrate became neutral, and the obtained copper oxide composite graphite composite was obtained. Is dried in a vacuum (implemented at 85 ° C. to prevent the progress of oxidation during drying) and pulverized. The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 79.
6: 20.4. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

Preparation of Negative Electrode A nonionic dispersant was added to the copper oxide-deposited graphite composite prepared by the above-described method, and polytetrafluoroethylene (after drying, the copper oxide-deposited graphite composite and polytetrafluoroethylene were mixed together). A dispersion liquid having a weight ratio of 87:13) was added to form a paste, which was applied to both surfaces of a copper foil current collector. This was dried at 60 ° C., heat-treated at 240 ° C. in vacuum or in a nitrogen gas, cooled to room temperature, pressed, and further dried at 200 ° C. under reduced pressure to remove moisture, and used as a negative electrode. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 74 μm (a current collector thickness of 50 μm).

Evaluation of Negative Electrode Current was collected from the copper current collector with a lead wire, and used as an electrode for evaluation. The evaluation was performed using a three-electrode method, and lithium was used as a counter electrode and a reference electrode. The electrolytic solution is obtained by dissolving 1 mol / l of lithium perchlorate in a 1: 1 mixed solvent of ethylene carbonate and diethyl carbonate. The charge / discharge test is
The battery was initially charged to 0 V at a current density of 0.1 mA / cm ² , and subsequently discharged to 1.5 V at the same current. 2
The charge and discharge were repeated in the same potential range and current density after the first time, and the negative electrode was evaluated by the discharge capacity.

As a result, the discharge capacity in the second cycle was 456 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 420 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 2 Modified graphite (flaky, particle size 8 μm, d ₀₀₂₎ was used as graphite particles.
Is 0.337 nm, Lc is 17 nm, La is 12 nm,
An R value of 0.1 and a specific surface area of 9 m ² / g) were used and subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, 120 parts by weight of the above graphite powder and 66.7 parts by weight (molar ratio: 100: 3.33) of copper acetate hydrate (Cu (CH ₃ COO) ₂ .H ₂ O) were measured in a beaker. Take and mix well. In this, lithium hydroxide (LiOH
140 parts by weight of H ₂ O (10 parts by mole relative to Cu ²⁺ )
2 times), stir well, and add 2000 ml of ion-exchanged water.
Add and stir Cu (CH ₃ COO) ₂ .H ₂ O and Li
After OH · H ₂ O is dissolved, the mixture is heated on a hot plate kept at 90 ° C. for 20 hours. Replenish ion-exchanged water as needed with evaporation. Thereafter, the heating was terminated, and the mixture was allowed to stand at room temperature (about 20 ° C.) for 12 hours.
m), suction-filtered, washed with water until the filtrate became neutral, and vacuum-dried the obtained solid substance of the copper oxide composite graphite composite (implemented at 85 ° C. to prevent the progress of oxidation during drying). And pulverize. The weight ratio of graphite to copper oxide of the graphite oxide-adhered graphite powder thus produced was 82:18. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

A negative electrode was prepared by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 71 μm (the current collector had a thickness of 5 μm).
0 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 459 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 433 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 3 Modified graphite (flaky, particle size 17 μm, d
₀₀₂ is 0.337 nm, Lc is 22 nm, La is 15 n
m and R values were 0.1, and the specific surface area was 9 m ² / g), and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

[0045] First, the above-described graphite powder 120 parts by weight of copper sulfate pentahydrate _{(CuSO 4 · 5H 2 O)} 46.7 parts by weight (molar ratio 100: 1.87) and mixed well weighed into a beaker . Lithium hydroxide (LiOH / H ₂ O)
157 Stir well added (20-fold by molar ratio with respect to Cu ²⁺⁾ parts by weight, was added and stirred 2000ml deionized water, after CuSO ₄ · 5H ₂ O and LiOH · H ₂ O is dissolved, hold the 90 ° C. Heat on a hot plate for 20 hours. Replenish ion-exchanged water as needed with evaporation. Thereafter, the heating is terminated, and after leaving at room temperature (about 20 ° C.) for 12 hours,
Suction-filtered with a glass separator filter paper (pore diameter 1 μm), washed with water until the filtrate is neutral, and the obtained solid of the copper oxide composite graphite composite is vacuum dried (to prevent the progress of oxidation during drying). (Implemented at 85 ° C.) and pulverized. The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 8%.
9:11. The powder X of the graphite composite adhering to copper oxide
When the line wide-angle diffraction measurement was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 89 μm (the current collector had a thickness of 5 μm).
0 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 440 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 414 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 4 As graphite particles, artificial graphite (flaky, particle size 35 μm, d
₀₀₂ is 0.336 nm, Lc is 22 nm, La is 13 n
m and R values were 0, and the specific surface area was 4 m ² / g), and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

Firstly, the above-described graphite powder 120 parts by weight of copper sulfate pentahydrate _{(CuSO 4 · 5H 2 O)} 58.4 parts by weight (molar ratio 200: 4.67) and mixed well weighed into a beaker . Lithium hydroxide (LiOH / H ₂ O)
Add 98 parts by weight (10 times in molar ratio to Cu ²⁺ ), mix well, add 2,000 ml of ion-exchanged water and stir,
After CuSO ₄ · 5H ₂ O and LiOH · H ₂ O is dissolved,
Heat on a hot plate maintained at 90 ° C. for 20 hours. Replenish ion-exchanged water as needed with evaporation. afterwards,
After heating was completed and left at room temperature (about 20 ° C.) for 12 hours, the solution was suction-filtered with a glass separator filter paper (pore size: 1 μm), washed with water until the filtrate became neutral, and the obtained copper oxide composite graphite composite was obtained. Is dried in a vacuum (implemented at 85 ° C. to prevent the progress of oxidation during drying) and pulverized. The weight ratio of graphite to copper oxide in the graphite oxide-adhered graphite powder thus prepared was 86.
6: 13.4. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 130 μm (the thickness of the current collector was 50 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 400 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 385 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 5 As graphite particles, artificial graphite (spherical, particle diameter 6 μm, d ₀₀₂ 0.339 nm, Lc 25 nm, La 13 nm, R
A value of 0.4 and a specific surface area of 8 m ² / g) were used and subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, 120 g of the above-mentioned graphite powder and copper sulfate 5
19.7 g of hydrate (CuSO ₄ .5H ₂ O)
00: 0.79) into a beaker and mix well.
Among them, special grade 28% ammonia water (NH ₄ OH) 600
ml (about 10 times the molar ratio of ammonia to Cu ²⁺ )
Is added and stirred well, and 1400 ml of ion-exchanged water is added and stirred. After CuSO ₄ .5H ₂ O is dissolved, the mixture is heated on a hot plate kept at 70 ° C. for 10 hours. Replenish ion-exchanged water as needed with evaporation. After that, heating is finished and 1
After leaving at room temperature (about 20 ° C.) for 2 hours, the mixture was suction-filtered with a glass separator filter paper (pore size: 1 μm), washed with water until the filtrate became neutral, and the obtained solid of the copper oxide composite graphite composite was removed. Vacuum drying (implemented at 85 ° C. to prevent the progress of oxidation during drying) and pulverization. The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 95: 5. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

A negative electrode was prepared by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 70 μm (the current collector had a thickness of 5 μm).
0 μm).

This negative electrode was described in Example 1, except that 1 mol / l of lithium perchlorate dissolved in a 2: 1: 2 mixed solvent of ethylene carbonate, propylene carbonate, and diethyl carbonate was used as the electrolyte. Was evaluated in the manner described.

As a result, the discharge capacity in the second cycle was 421 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 395 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 6 The same artificial graphite (spherical, particle size 6) as in Example 5 was used as graphite particles.
μm, d ₀₀₂ is 0.339 nm, Lc is 25 nm, La
Was 13 nm, the R value was 0.4, and the specific surface area was 8 m ² / g). The copper oxide composite treatment was performed by the following method.

[0060] First, graphite powder 120 parts by weight of copper sulfate pentahydrate (CuSO ₄ · 5H ₂ O) of the above 19.7 parts by weight (molar ratio 100: 1) and mixed well weighed into a beaker. 95 parts by weight of urea (NH ₂ CONH ₂ ) (Cu
²⁺ stirring well was added approximately 10-fold) in a molar ratio with respect to, and stirred added 2000ml of deionized water, CuSO ₄ · 5
After H ₂ O and NH ₂ CONH ₂ are dissolved, the mixture is heated on a hot plate maintained at 90 ° C. for 20 hours. Replenish ion-exchanged water as needed with evaporation. After that, heating is finished and 1
After leaving at room temperature (about 20 ° C.) for 2 hours, the mixture was suction-filtered with a glass separator filter paper (pore size: 1 μm), washed with water until the filtrate became neutral, and the obtained solid of the copper oxide composite graphite composite was removed. Vacuum drying (implemented at 85 ° C. to prevent the progress of oxidation during drying) and pulverization. The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 95: 5. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 72 μm (the current collector had a thickness of 5 μm).
0 μm).

Example 1 was repeated except that this negative electrode was prepared by dissolving 1 mol / l lithium perchlorate in a 2: 1: 2 mixed solvent of ethylene carbonate, propylene carbonate and diethyl carbonate in the electrolyte. Evaluation was performed by the method described.

As a result, the discharge capacity in the second cycle was 424 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 396 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 1 Natural graphite produced in Madagascar used in Example 1 was used as graphite particles, and electroless copper plating was applied to the natural graphite. Electroless copper plating was performed by the following method.

First, the graphite powder was immersed in ethyl alcohol, dried and sensitized (30 g / l SnCl ₂ .2).
H ₂ O and a mixed solution of 20 ml / l concentrated hydrochloric acid), and further activated (0.4 g / l PbCl ₂ .2H ₂ O)
And 3 ml / l of concentrated hydrochloric acid) to carry out pretreatment. Next, 10 g of the pretreated graphite powder was
g / l CuSO ₄ .5H ₂ O, 50 g / l sodium potassium tartrate, 10 g / l sodium hydroxide, 10 g / l
A solution in which 37% formalin (ml / l) was dissolved was added to an electroless copper plating bath adjusted to pH 12.0 with sodium hydroxide, and the graphite powder was copper-plated at room temperature while stirring the solution with a stirrer. . This was dried at 60 ° C.
The weight ratio of graphite to copper in the resulting copper-coated graphite powder was 83: 1.
It was 7. This copper-coated graphite powder was oxidized in air at 250 ° C. for 5 hours to obtain a graphite composite to which copper oxide had adhered. When a powder X-ray wide-angle diffraction measurement of the thus-obtained graphite composite attached with copper oxide was performed, diffraction lines derived from graphite and diffraction lines derived from cupric oxide were observed. Further, the weight ratio of graphite to copper oxide in the copper oxide-adhered graphite composite was 79.6: 20.4.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the prepared negative electrode was 8 cm ² , and the thickness was 75 μm (the thickness of the current collector was 5 μm).
0 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 458 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 421 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 2 The modified graphite used in Example 2 was used as graphite particles.
CuSO ₄ · 5H ₂ O of 0.06mol / l, 0.3mo
1 / l EDTA, 0.4 mol / l formaldehyde, 170 mg / l solution of 7-iodo-8-hydroxyquinoline-5-sulfonic acid dissolved in sodium hydroxide adjusted to pH 12.8 7 in copper plating bath
Except that plating was performed at 5 ° C., the procedure was performed as described in Example 1, and the weight ratio of graphite to copper of the resulting copper-coated graphite powder was 85:15. This copper-coated graphite powder is placed in air 4
Oxidation treatment was performed at 00 ° C. for 30 minutes to produce a graphite composite with copper oxide. When the powder X-ray wide-angle diffraction measurement of the thus obtained copper oxide-adhered graphite composite was performed, diffraction lines derived from graphite and diffraction lines derived from cupric oxide were observed,
It was found to be graphite and cupric oxide. further,
The weight ratio of graphite to copper oxide in the graphite composite with copper oxide was 82:18.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the produced negative electrode was 8 cm ² , and the thickness was 71 μm (the thickness of the current collector was 5 μm).
0 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 462 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 435 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 3 The modified graphite used in Example 3 was used as graphite particles.
5 g / l Cu (NO ₃ ) ₂ .3H ₂ O, 10 g / l sodium bicarbonate, 30 g / l sodium potassium tartrate, 20 g / l sodium hydroxide, 100 ml / l
Was prepared in the same manner as in Example 1 except that plating was performed using an electroless copper plating bath adjusted to pH 11.5 with sodium hydroxide by dissolving a solution in which 37% formalin was dissolved. The weight ratio of graphite to copper in the graphite powder is 9
1: 9. This copper-coated graphite powder is placed in oxygen at 200 ° C.
For 24 hours to produce a copper oxide-adhered graphite composite. The powder X of the copper oxide-adhered graphite composite thus obtained
When the line wide angle diffraction measurement was performed, diffraction lines derived from graphite and diffraction lines derived from cupric oxide were observed, and it was found that the particles were graphite and cupric oxide. Further, the weight ratio of graphite to copper oxide in the graphite composite with copper oxide attached was 89:
It was 11.

A negative electrode was prepared by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 88 μm (the current collector had a thickness of 5 μm).
0 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 439 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 415 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 4 The artificial graphite used in Example 4 was used as graphite particles.
Cu · SO ₄ · 5H ₂ O of 0 g / l, NiS of 15 g / l
O ₄ · 7H ₂ O, and the solution prepared by dissolving the hydrazine sulfate in 45 g / l, sodium potassium tartrate 180 g / l, sodium hydroxide 45 g / l, a 15 g / l solution obtained by dissolving sodium carbonate Except that plating was performed using an electroless copper plating bath mixed immediately before use, the method was carried out in the same manner as described in Example 1, and the weight ratio of graphite to copper in the resulting copper-coated graphite powder was 89:11. Was. This copper-coated graphite powder was oxidized in air at 350 ° C. for 1 hour to prepare a copper oxide-adhered graphite composite. When a powder X-ray wide-angle diffraction measurement of the thus obtained copper oxide-adhered graphite composite was performed, diffraction lines derived from graphite and diffraction lines derived from cupric oxide were observed, which were graphite and cupric oxide. I understand. Further, the weight ratio of graphite to copper oxide in the graphite composite with copper oxide was 86.6: 13.4.

A negative electrode was manufactured by the method described in Example 1 using the copper oxide-adhered graphite composite. The produced negative electrode had a surface area of 8 cm ² and a thickness of 132 μm (the thickness of the current collector was 50 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 402 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 388 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 5 The artificial graphite used in Example 5 was used as graphite particles, and MAC-100 (manufactured by Okuno Pharmaceutical Co., Ltd.) and MAC-200 (manufactured by Okuno Pharmaceutical Co., Ltd.) were used as pretreatment liquids.
, And plating was performed by the method described in Comparative Example 1 except that a two-component type electroless copper plating bath (manufactured by Okuno Pharmaceutical Co., Ltd.) of MAC-500A and MAC-500B was used, and the resulting copper coating was formed. The weight ratio of graphite to copper in the graphite powder is 9
6: 4. This copper-coated graphite powder was oxidized at 70 ° C. in water containing dissolved oxygen for 15 hours to prepare a copper oxide-adhered graphite composite. When a powder X-ray wide-angle diffraction measurement of the thus obtained copper oxide-adhered graphite composite was performed, diffraction lines derived from graphite and diffraction lines derived from cuprous oxide and cupric oxide were observed. It turned out to be a mixture of cuprous oxide and cupric oxide. Further, the weight ratio of graphite to copper oxide in the graphite composite with copper oxide was 95.2:
4.8.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the produced negative electrode was 8 cm ² , and the thickness was 71 μm (the thickness of the current collector was 5 μm).
0 μm).

This negative electrode was described in Example 1 except that 1 mol / l of lithium perchlorate dissolved in a 2: 1: 2 mixed solvent of ethylene carbonate, propylene carbonate and diethyl carbonate was used as the electrolyte. Was evaluated in the manner described.

As a result, the discharge capacity in the second cycle was 425 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 398 mAh per unit volume of the electrode (excluding the volume of the current collector).

Table 1 shows the results of Examples 1 to 6 and Comparative Examples 1 to 5.
Shown in From these results, it was found that when a negative electrode containing a graphite composite with copper oxide was used, a high-capacity discharge capacity comparable to that obtained by plating was obtained. Also, comparing the simplicity of the steps, it can be seen that, as shown in FIG. 1, substantially two steps can be omitted in the present invention, and the workability is improved.

[0086]

[Table 1]

Comparative Example 6 A negative electrode was produced in the same manner as in Example 1 except that only the natural graphite produced in Madagascar used in Example 1 was used. The surface area of the produced negative electrode was 8 cm ² , and the thickness was 85 μm (the thickness of the current collector was 50 μm).

The negative electrode was evaluated by the method described in Example 1 except that the current density was 30 mA / g.

As a result, the discharge capacity in the second cycle was 358 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 344 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 7 The natural graphite produced in Madagascar used in Example 1 was used as the main negative electrode active material, and this was mixed with a commercially available reagent cupric oxide (particle diameter 27 μm) in a mortar at a weight ratio of 80:20. , A nonionic dispersant is added, and the weight ratio of polytetrafluoroethylene (a mixture of graphite and cupric oxide after drying and polytetrafluoroethylene is 87: 1)
(3) was added into a paste by adding the dispersion liquid to the copper foil current collector. 60 ℃
, Heat-treated at 240 ° C., pressed, and further dried at 200 ° C. under reduced pressure to remove moisture, and used as a negative electrode. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 138 μm.
m (the thickness of the current collector is 50 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 371 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 335 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 8 Mesocarbon microbeans carbonized at 1000 ° C. as carbon particles (spherical, particle diameter 6 μm, d ₀₀₂ 0.349)
nm and Lc are 1.3 nm, La cannot be calculated, R value is 1.3, specific surface area is 1 m ² / g), and MAC-100 (manufactured by Okuno Pharmaceutical Co., Ltd.) and MA are used as pretreatment liquids.
MAC using C-200 (manufactured by Okuno Pharmaceutical Co., Ltd.)
Using a two-liquid type electroless copper plating bath (manufactured by Okuno Pharmaceutical Co., Ltd.) of -500A and MAC-500B, the copper coating was performed by the method described in Example 1 except that the plating bath was performed. The weight ratio of carbon to copper in the carbon powder is 81:19.
Met. This copper-coated carbon powder was further oxidized by the method described in Example 1 to produce a copper oxide-adhered carbon composite. When a powder X-ray wide-angle diffraction measurement of the thus obtained copper oxide-adhered carbon composite was performed, diffraction lines derived from carbon and diffraction lines derived from cupric oxide were observed, which were carbon and cupric oxide. I understand. Further, the weight ratio of carbon to copper oxide in the copper oxide-adhered carbon composite was 77.
3: 22.7.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 68 μm (the current collector had a thickness of 5 μm).
0 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 176 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 159 mAh per unit volume of the electrode (excluding the volume of the current collector).

Table 1 shows the results of Examples 1 to 6 and Comparative Examples 6 to 8.
Shown in From these, when the copper oxide-adhered graphite composite produced by the method shown in the examples is a negative electrode composed of a composite of graphite and copper oxide, the copper oxide-adhered composite electrode produced by the method shown in the comparative example It was found that a high-capacity discharge capacity comparable to that obtained was obtained. When the composite was not a composite with graphite (Comparative Example 8), the capacity was found to be low.

Example 7 As graphite particles, artificial graphite (flaky, particle size 77 μm, d
₀₀₂ is 0.337 nm, Lc is 26 nm, La is 14 n
The m and R values were 0.1, the specific surface area was 2 m ² / g), the same reagents were used in the same manner as in Example 1, the mixing ratio was changed, and a graphite composite with copper oxide was prepared. The weight ratio of graphite to copper oxide in the resulting graphite composite powder with copper oxide was 8%.
4.3: 15.7. Further, when the powdered X-ray wide-angle diffraction measurement of the produced graphite composite attached with copper oxide was performed, it was found to be graphite and cupric oxide.

A negative electrode was prepared by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 225 μm (the thickness of the current collector was 50 μm).

Evaluation was made by the method described in Example 1 except that the current density of this negative electrode was 0.05 mA / cm ² .

As a result, the discharge capacity in the second cycle was 370 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 349 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 9 As graphite particles, artificial graphite (flaky, particle size 117 μm, d
₀₀₂ is 0.337 nm, Lc is 25 nm, La is 17 n
The plating was performed by the method described in Comparative Example 5 using m and R values of 0.1 and a specific surface area of 1 m ² / g), and the weight ratio of graphite to copper of the resulting copper-coated graphite powder was 88: It was 12.

This copper-coated graphite powder was oxidized by the method described in Comparative Example 1 to produce a copper oxide-adhered graphite composite. When a powder X-ray wide-angle diffraction measurement of the thus obtained copper oxide-adhered graphite composite was performed, diffraction lines derived from graphite and diffraction lines derived from cupric oxide were observed, which were graphite and cupric oxide. I understand. Further, the weight ratio of graphite to copper oxide in the copper oxide-adhered graphite composite was 85.4: 1.
4.6.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the produced negative electrode was 8 cm ² , and the thickness was 305 μm (the thickness of the current collector was 50 μm).

Evaluation was made by the method described in Example 1 except that the current density of this negative electrode was 0.05 mA / cm ² .

As a result, the discharge capacity in the second cycle was 361 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 337 mAh per unit volume of the electrode (excluding the volume of the current collector).

Table 1 shows the results of Examples 1 to 7 and Comparative Example 9. This proved that graphite having a particle size of 80 μm or less was good.

Example 8 A graphite composite with copper oxide was prepared in the same manner as in Example 4 except that natural graphite produced in Madagascar was used as the graphite particles. The weight ratio of graphite to copper oxide in the resulting copper oxide-adhered graphite composite powder was 86.6: 13:
It was 4. Further, when the powdered X-ray wide-angle diffraction measurement of the produced graphite composite attached with copper oxide was performed, it was found to be graphite and cupric oxide.

A nonionic dispersant was added to the copper oxide-deposited graphite composite produced by the above-described method, and polytetrafluoroethylene (after drying, the weight ratio of the copper oxide-deposited graphite composite to polytetrafluoroethylene was 77%). : 23) to obtain a paste.
It was applied on both sides of the copper foil current collector. This is dried at 60 ° C., 2
Heat treatment was performed at 40 ° C. in a vacuum or in nitrogen gas, cooled to room temperature, pressed, and dried at 200 ° C. under reduced pressure to remove moisture. This negative electrode has a surface area of 8
cm ² , the thickness of the electrode is 83 μm (the thickness of the current collector is 50 μm).
m).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 386 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 358 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 10 The material described in Example 8 was used for the copper oxide-adhered graphite composite.

After drying, a negative electrode was prepared in the same manner as in Example 1 except that the weight ratio of the graphite composite with copper oxide and polytetrafluoroethylene was changed to 63:37. The surface area of the produced negative electrode was 8 cm ² , and the thickness of the electrode was 88 μm (the thickness of the current collector was 50 μm).

This negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 362 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 344 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 9 The material described in Example 8 was used for a graphite composite with copper oxide.

After drying, a negative electrode was prepared in the same manner as in Example 1, except that the weight ratio of the graphite composite with copper oxide and polytetrafluoroethylene was changed to 97: 3. The surface area of the produced negative electrode was 8 cm ² , and the thickness of the electrode was 76 μm (the thickness of the current collector was 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 413 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 350 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 11 The material described in Example 8 was used as the graphite composite attached with copper oxide.

After drying, a negative electrode was prepared in the same manner as in Example 1 except that the weight ratio of the graphite composite with copper oxide to polytetrafluoroethylene was 99.5: 0.5. Peeled from the body.

Table 2 shows the results of Examples 8 and 9 and Comparative Examples 10 and 11. From this and Examples 1 to 7, it was found that the optimal weight ratio of the graphite composite with copper oxide to the binder was 99: 1 to 70:30.

[0123]

[Table 2]

Example 10 As graphite particles, artificial graphite (flaky, particle size 7 μm, d ₀₀₂₎
Is 0.336 nm, Lc is 22 nm, La is 13 nm,
An R-value of 0.1 and a specific surface area of 10 m ² / g) were used in the same manner as in Example 4 except that a specific surface area of 10 m ² / g was used, and a graphite composite with a copper oxide was prepared. The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide attached at this time was 86.6: 13.4.
Met. Moreover, when the powdered X-ray wide-angle diffraction measurement of the produced graphite composite with copper oxide was performed, it was found to be graphite and cupric oxide.

[0125] The copper oxide-adhered graphite composite prepared by the above-described method is prepared by dissolving polyvinylidene fluoride in N, N-dimethylformamide in advance (the weight ratio of N, N-dimethylformamide to polyvinylidene fluoride is 1.
5: 0.05) and made into a paste. At this time, the weight ratio after drying of the graphite composite with copper oxide and polyvinylidene fluoride was mixed so as to be 91: 9. This paste was applied on both surfaces of a stainless steel foil current collector. This was dried at 65 ° C., heat-treated at 155 ° C., and pressed, and further dried at 160 ° C. under reduced pressure to remove moisture, and used as a negative electrode. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 72 μm (a current collector thickness of 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 440 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 414 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 11 Modified graphite (flaky, particle size 7 μm, d ₀₀₂₎ was used as graphite particles.
Is 0.336 nm, Lc is 22 nm, La is 13 nm,
An R value of 0.1 and a specific surface area of 10 m ² / g) were used. A method described in Example 1 except that 120 parts by weight, 9.3 parts by weight, and 15.5 parts by weight of this graphite powder, copper sulfate pentahydrate, and lithium hydroxide were used, and 2000 ml of ion-exchanged water was used. Thus, a graphite composite with copper oxide was prepared. The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite composite powder thus obtained was 97.6: 2.4 (graphite / (graphite + copper oxide) =
0.976). Moreover, when the powdered X-ray wide-angle diffraction measurement of the produced graphite composite with copper oxide was performed, it was found to be graphite and cupric oxide.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 70 μm (the current collector had a thickness of 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 396 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 372 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 12 The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide was 93.8: 6.2 (graphite / (graphite + copper oxide) = 0.93).
A graphite composite to which copper oxide was attached was prepared using the materials and methods described in Example 11, except that the raw materials were prepared so as to satisfy 8).

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 78 μm (the current collector had a thickness of 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 535 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 499 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 13 A raw material was prepared so that the weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide was 89:11 (graphite / (graphite + copper oxide) = 0.89). A copper oxide-adhered graphite composite was produced using the materials and methods described in Example 11.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the produced negative electrode was 8 cm ² , and the thickness was 76 μm (the thickness of the current collector was 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 424 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 410 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 14 The weight ratio of graphite to copper oxide in the graphite composite powder adhering to copper oxide was 79.6: 20.4 (graphite / (graphite + copper oxide) = 0.7).
Except that the raw materials were prepared so as to satisfy 96), a graphite composite with copper oxide was prepared by using the materials and methods described in Example 11.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 80 μm (the current collector had a thickness of 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 420 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 403 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 15 The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide was 72.8: 27.2 (graphite / (graphite + copper oxide) = 0.7).
Except that the raw materials were prepared so as to satisfy 28), a graphite composite with copper oxide was prepared using the materials and methods described in Example 11.

A negative electrode was produced by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the prepared negative electrode was 8 cm ² , and the thickness was 79 μm (the thickness of the current collector was 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 380 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 366 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 16 The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide attached was 59.3: 40.7 (graphite / (graphite + copper oxide) = 0.5).
Except that the raw materials were prepared so as to satisfy 93), a graphite composite attached with copper oxide was produced using the materials and methods described in Example 11.

A negative electrode was prepared by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 83 μm (the current collector had a thickness of 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 372 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 355 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 17 The weight ratio of graphite to copper oxide in the graphite composite powder to which copper oxide was attached was 61.9: 38.1 (graphite / (graphite + copper oxide) = 0.6).
A graphite composite to which copper oxide was attached was prepared using the materials and methods described in Example 11 except that the raw materials were prepared so as to satisfy 19).

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the produced negative electrode was 8 cm ² and the thickness was 81 μm (the thickness of the current collector was 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 375 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 347 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 18 A raw material was prepared so that the weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide was 57:43 (graphite / (graphite + copper oxide) = 0.57). A copper oxide-adhered graphite composite was produced using the materials and methods described in Example 11.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 85 μm (the current collector had a thickness of 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 369 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 344 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 12 Modified graphite (flaky, particle size 7 μm, d ₀₀₂ 0.336 n
m, Lc is 22 nm, La is 13 nm, R value is 0.1,
A negative electrode was produced by the method described in Example 1 using only the specific surface area of 10 m ² / g, that is, the weight ratio was 1 (graphite / (graphite + copper oxide) = 1). The surface area of the prepared negative electrode is 8c
m ² , and the thickness is 77 μm (the thickness of the current collector is 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 361 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 340 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 13 The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide attached was 98.8: 1.2 (graphite / (graphite + copper oxide) = 0.98).
A graphite composite to which copper oxide was attached was prepared using the materials and methods described in Example 11, except that the raw materials were prepared so as to satisfy 8).

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The produced negative electrode had a surface area of 8 cm ² and a thickness of 72 μm (the current collector had a thickness of 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 363 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 331 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 14 The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide attached was 53.5: 46.5 (graphite / (graphite + copper oxide) = 0.5).
Except that the raw materials were blended so as to satisfy 35), a graphite composite with copper oxide was prepared using the materials and methods described in Example 11.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the prepared negative electrode was 8 cm ² , and the thickness was 87 μm (the thickness of the current collector was 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 351 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 314 mAh per unit volume of the electrode (excluding the volume of the current collector).

Comparative Example 15 The weight ratio of graphite to copper oxide in the graphite composite powder with copper oxide attached was 47.5: 52.5 (graphite / (graphite + copper oxide) = 0.4).
Except that the raw materials were prepared so as to satisfy the condition (75), a graphite composite with copper oxide was prepared by using the materials and methods described in Example 11.

A negative electrode was manufactured by the method described in Example 1 using the graphite composite with copper oxide. The surface area of the prepared negative electrode was 8 cm ² , and the thickness was 86 μm (the thickness of the current collector was 5 μm).
0 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 319 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 302 mAh per unit volume of the electrode (excluding the volume of the current collector).

Examples 10 to 18 and Comparative Examples 7, 12 to 15
Table 3 shows the results. Regarding these, the weight ratio of the graphite composite adhering to the copper oxide and the weight ratio of the composite and the treated copper oxide to the mixture, and the discharge per unit volume (excluding the volume of the current collector) of the electrode in the second cycle FIG. 2 shows the relationship between the capacitances. Accordingly, it is preferable that the weight ratio of the graphite and the composited copper oxide is in the range of 98.5: 1.5 to 55:45, and is in the range of 98.5: 1.5 to 72:28. Has proven to be particularly preferred. Further, when a mere reagent or the like is mixed, the discharge capacity becomes relatively small and the characteristics are not so good.

[0176]

[Table 3]

Example 19 As graphite particles, artificial graphite (flaky, particle size 7 μm, d ₀₀₂₎
Is 0.336 nm, Lc is 22 nm, La is 13 nm,
An R value of 0.1 and a specific surface area of 10 m ² / g) were used and subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the material and method described in Example 3. The difference is that the melt is heated on a hot plate maintained at 80 ° C. for 20 hours and then left at room temperature (about 20 ° C.) for 28 hours, and the graphite and copper oxide of the copper oxide-adhered graphite powder thus produced is The weight ratio was 89:11. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

When the particle diameters of graphite and copper oxide in the graphite composite powder with copper oxide were measured by SEM, the average particle diameters were 7.5 μm and 2.5 μm, respectively.

The copper oxide-adhered graphite composite prepared by the above-described method is prepared by dissolving polyvinylidene fluoride in N, N-dimethylformamide in advance (the weight ratio of N, N-dimethylfolimamide to polyvinylidene fluoride is ,
1.5: 0.05) and made into a paste.
At this time, the graphite oxide-adhered graphite composite and polyvinylidene fluoride were mixed so that the weight ratio after drying was 91: 9.
This paste was applied on both sides of a stainless steel foil current collector. This was dried at 65 ° C., heat-treated at 155 ° C., pressed, and further dried at 160 ° C. under reduced pressure to remove moisture, and used as a negative electrode. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 85 μm (a current collector thickness of 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 451 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 427 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 20 The artificial graphite of Example 19 was used as graphite particles, and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the materials and methods described in Example 3. The difference is that after heating the melt in a thermostat at 80 ° C. for 20 hours,
The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder prepared in this way was 8 hours at room temperature (about 20 ° C.).
9:11. The powder X of the graphite composite adhering to copper oxide
When the line wide-angle diffraction measurement was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

When the particle diameters of graphite and copper oxide in the graphite composite powder with copper oxide were measured by SEM, the average particle diameters were 7.5 μm and 3 μm, respectively.

A negative electrode was produced in the same manner as in Example 19, using the graphite composite adhering to copper oxide produced by the above-described method. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 86 μm.
m (the thickness of the current collector is 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 448 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 426 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 21 The artificial graphite of Example 19 was used as graphite particles, and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the materials and methods described in Example 3. The difference is that the lysate is cooked for 10 hours on a direct heat and then for 24 hours at room temperature (about 20 ° C).
The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 89:11. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

When the particle diameters of graphite and copper oxide in the graphite composite powder with copper oxide were measured by SEM, the average particle diameters were 7.5 μm and 1.8 μm, respectively.

A negative electrode was produced in the same manner as in Example 19, using the graphite composite with copper oxide produced in the manner described above. This negative electrode had a surface area of 8 cm ² and an electrode thickness of 85 μm.
m (the thickness of the current collector is 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 453 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 421 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 22 The artificial graphite of Example 19 was used as graphite particles, and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the materials and methods described in Example 3. The difference is that after heating the melt in a thermostat at 120 ° C. for 10 hours,
The weight ratio of graphite to copper oxide in the thus-prepared graphite powder with copper oxide is 8 in that it is left at room temperature (about 20 ° C.) for 4 hours.
9:11. The powder X of the graphite composite adhering to copper oxide
When the line wide-angle diffraction measurement was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

The particle diameters of graphite and copper oxide in the graphite composite powder with copper oxide were measured by SEM to find that the average particle diameters were 7.5 μm and 1.5 μm, respectively.

A negative electrode was produced in the same manner as in Example 19, using the graphite composite with copper oxide produced in the manner described above. This negative electrode had a surface area of 8 cm ² and an electrode thickness of 84 μm.
m (the thickness of the current collector is 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 455 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 423 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 23 As the graphite particles, the artificial graphite of Example 19 was used and subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the material and method described in Example 3. The difference is that after heating the melt in a thermostat at 80 ° C. for 20 hours,
The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 8 points at 24 hours in a constant temperature bath at a constant temperature of 8 ° C.
9:11. The powder X of the graphite composite adhering to copper oxide
When the line wide-angle diffraction measurement was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

When the particle diameters of graphite and copper oxide in the graphite composite powder with copper oxide were measured by SEM, the average particle diameters were 7.5 μm and 3.9 μm, respectively.

A negative electrode was produced in the same manner as in Example 19, using the graphite composite adhering to copper oxide produced by the above-described method. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 88 μm.
m (the thickness of the current collector is 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 445 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 418 mAh per unit volume of the electrode (excluding the volume of the current collector).

Example 24 The artificial graphite of Example 19 was used as graphite particles, and this was subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the material and method described in Example 3. The difference is that the melt is heated on a hot plate maintained at 80 ° C. for 20 hours and then immediately suction-filtered with a glass separator filter paper (pore diameter 1 μm). Was washed out with water until the filtrate became neutral. During this time, the outflow of fine particles continued. The obtained solid material of the copper oxide composite graphite composite is vacuum-dried (implemented at 85 ° C. in order to prevent the progress of oxidation during drying) and pulverized. The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 95: 5. When the powder X-ray wide-angle diffraction measurement of the graphite composite attached with copper oxide was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed. As a precautionary measure, the fine particle portion was also dried and solidified, and a powder X-ray wide-angle diffraction measurement was performed. As a result, a diffraction line derived from cupric oxide was observed.

When the particle diameters of graphite and copper oxide of the graphite composite powder with copper oxide were measured by SEM, the average particle diameters were 7.5 μm and 1.2 μm, respectively. It was 0.3 μm.

As described above, the amount of copper oxide produced far from the amount of copper oxide expected from the charged amount of raw materials was obtained, and it was found that it was difficult to control the amount of compounding.

However, the negative electrode (surface area: 8 cm ² , electrode thickness: 71 μm (current collector thickness: 50 μm)) was prepared in the same manner as in Example 19, using the copper oxide-adhered graphite composite produced by the above method. Was prepared and evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 411 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 396 mAh per unit volume of the electrode (excluding the volume of the current collector), and was a characteristic expected from the weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder.

Comparative Example 16 As the graphite particles, the artificial graphite of Example 19 was used and subjected to a copper oxide composite treatment. The copper oxide composite treatment was performed by the following method.

First, the above-mentioned graphite powder is processed according to the materials and methods described in Example 3. The difference is that after heating the melt in a thermostat at 80 ° C. for 20 hours,
The weight ratio of graphite to copper oxide in the copper oxide-adhered graphite powder thus produced was 8 points at 120 ° C. in a constant temperature bath.
9:11. The powder X of the graphite composite adhering to copper oxide
When the line wide-angle diffraction measurement was performed, a diffraction line derived from graphite and a diffraction line derived from cupric oxide CuO were observed.

Further, when the particle diameters of graphite and copper oxide of the graphite composite powder with copper oxide were measured by SEM, the average particle diameters were 7.5 μm and 9 μm, respectively.

A negative electrode was produced in the same manner as in Example 19, using the graphite composite with copper oxide produced by the above method. This negative electrode has a surface area of 8 cm ² and an electrode thickness of 90 μm.
m (the thickness of the current collector is 50 μm).

The negative electrode was evaluated by the method described in Example 1.

As a result, the discharge capacity in the second cycle was 408 mA per unit volume of the electrode (excluding the volume of the current collector).
h, the discharge capacity at the 10th cycle was 395 mAh per unit volume of the electrode (excluding the volume of the current collector).

The results of Examples 19 to 24 and Comparative Example 16 are shown in Table 4. Thereby, it is preferable that the particle diameter of the copper oxide to be composited with the graphite of the copper oxide-adhered graphite composite is about 1 μm or more in view of the manufacturing process derived from the characteristics of the glass filter, It has been found that it is preferable to be within the range of the particle size or less. However, when other separation methods and water washing methods are used and the lower limit of the particle size is not defined by the characteristics of the glass filter, it is apparent that the range is simply smaller than the particle size of the graphite that is present at the same time.

[0220]

[Table 4]

Example 25 Production of Negative Electrode The material described in Example 8 was used for the graphite composite with copper oxide.

A nonionic dispersant was added to the copper oxide-deposited graphite composite produced by the above method, and polytetrafluoroethylene (after drying, the weight ratio of the copper oxide-deposited graphite composite to polytetrafluoroethylene was calculated as follows: (91: 9) was applied to a nickel three-dimensional porous current collector, and the paste was applied to the pores. This was dried at 60 ° C., heat treated at 240 ° C., pressed, and further dried at 200 ° C. under reduced pressure to remove moisture, and used as a negative electrode. This negative electrode has a diameter of 14.
It is a pellet with a thickness of 5 mm and an electrode thickness of 0.41 mm.

Preparation of Positive Electrode Lithium carbonate and cobalt carbonate and antimony trioxide were mixed at a ratio of lithium atom to cobalt atom and antimony atom of 1:
0.95: 0.05 each was weighed, mixed in a mortar, and baked in air at 900 ° C for 20 hours.
Then, the powder of the active material was obtained by crushing in a mortar.
This active material had a composition of Li _0.98 Co _0.95 Sb _0.05 O ₂ . The thus obtained positive electrode active material is mixed with acetylene black, a nonionic dispersant is added, and polytetrafluoroethylene (after drying, the weight ratio of the positive electrode active material to acetylene black and polytetrafluoroethylene is , 100: 10: 5), and the mixture was made into a paste by applying a dispersion liquid onto a titanium mesh current collector. This is dried at 60 ° C, 240 ° C
Press after heat treatment at 200 ° C.
The dried under reduced pressure was used as a positive electrode. This positive electrode
It is a pellet having a diameter of 14.5 mm and an electrode thickness of 0.93 mm.

Assembling of Battery As shown in FIG. 2, the positive electrode current collector 2 was previously attached to the inner bottom surface by welding, and the positive electrode 3 was crimped to the positive electrode can 1 on which the insulating packing 8 was placed. Next, a separator 7 of microporous polypropylene was placed on this, and 1 mol / l of Li was added to a mixed solvent of ethylene carbonate, propylene carbonate, and diethyl carbonate in a ratio of 2: 1: 3.
Impregnated with an electrolytic solution in which PF ₆ is dissolved. On the other hand, the negative electrode can 4
The negative electrode current collector 5 is welded to the inner surface of the substrate, and the negative electrode 6 is press-bonded to the negative electrode current collector. Next, the negative electrode 6 is overlaid on the separator 7, and the positive electrode can 1 and the negative electrode can 4 are caulked with the insulating packing 8 interposed therebetween, thereby producing a coin-type battery.

Evaluation of Battery The produced coin-type battery reached 4.2 V at a charging / discharging current of 2 mA and a charging upper limit voltage of 4.2 V, and was then charged at a constant voltage of 4.2 V, for a charging time of 12 hours. The capacity was measured with the lower limit voltage of the discharge being 2.5 V. The evaluation was performed on the discharge capacity of the battery.

As a result, the average voltage in the discharge was 3.7
V, and the discharge capacity at the second cycle was 19 mAh, 10
The discharge capacity at the cycle was 17 mAh.

Comparative Example 17 A negative electrode was produced by the method described in Example 25 using only natural graphite produced in Madagascar. The size and thickness of the produced negative electrode are the same. The positive electrode and the battery were also prepared in Example 25.
Was prepared by the method described in (1).

The battery was evaluated by the method described in Example 25.

As a result, the average voltage in the discharge was 3.7
V and the discharge capacity in the second cycle was 14 mAh, 10
The discharge capacity at the cycle was 13 mAh.

Example 26 Preparation of Negative Electrode The material described in Example 12 was used for a graphite composite with copper oxide.

A nonionic dispersant was added to the copper oxide-deposited graphite composite produced by the above-described method, and the mixture was dried with polytetrafluoroethylene (after drying, the weight ratio of the copper oxide-deposited graphite composite to polytetrafluoroethylene was changed to 91: 9) to form a paste.
The paste was applied to a nickel three-dimensional porous current collector, and a paste was applied to the holes. This was dried at 60 ° C., heat treated at 240 ° C., pressed, and further dried at 200 ° C. under reduced pressure to remove moisture, and used as a negative electrode. This negative electrode has a diameter of 1
It is a 4.5 mm pellet with an electrode thickness of 0.37 mm.

Preparation of Positive Electrode Lithium carbonate and manganese dioxide were each weighed so that the ratio of lithium atoms to manganese atoms was 1.1: 2, mixed in a mortar, and then in air at 900 ° C. for 3 days. The active material LiM is fired and then crushed in a mortar.
A powder of n ₂ O ₄ was obtained. The positive electrode active material thus obtained is mixed with a conductive material (a mixture of acetylene black and expanded graphite at a weight ratio of 2: 1), a nonionic dispersant is added, and polytetrafluoroethylene (after drying, The weight ratio between the positive electrode active material and the conductive material, polytetrafluoroethylene,
(100: 10: 5) was added to form a paste by adding a dispersion liquid to a titanium mesh current collector. This was dried at 60 ° C., heat-treated at 240 ° C., pressed, and dried at 200 ° C. under reduced pressure to remove moisture, and used as a positive electrode. This positive electrode has a diameter of 14.5.
mm, and the thickness of the electrode is 1.0 mm.

Battery assembly Ethylene carbonate and γ-butyrolactone were used in the electrolyte.
1m in a 3: 1: 3 mixed solvent with diethyl carbonate
A coin-type battery was produced by the method described in Example 18 except that a solution in which ol / l of LiPF ₆ was dissolved was used.

Evaluation of Battery The produced coin-type battery reached 4.2 V at a charging / discharging current of 1 mA and a charging upper limit voltage of 4.2 V, and was then charged at a constant voltage of 4.2 V. The charging time was set to 24 hours. . The capacity was measured with the lower limit voltage of the discharge being 2.5 V. The evaluation was performed on the discharge capacity of the battery.

As a result, the average voltage in the discharge was 3.7
V, and the discharge capacity at the second cycle is 20 mAh, 10
The discharge capacity at the cycle was 15 mAh.

Comparative Example 18 Modified graphite (flaky, particle size 7 μm, d ₀₀₂ 0.336 n
m, Lc is 22 nm, La is 13 nm, R value is 0.1,
A negative electrode was prepared by the method described in Example 25 using only the specific surface area (10 m ² / g). The size of the prepared negative electrode,
The thickness is the same. A positive electrode and a battery were also prepared by the method described in Example 25.

This battery was evaluated by the method described in Example 26.

As a result, the average voltage in the discharge was 3.7
V, and the discharge capacity in the second cycle was 13 mAh, 10
The discharge capacity at the cycle was 12 mAh.

The results of Examples 25 and 26 and Comparative Examples 17 and 18 are shown in Table 5. Thus, a high-capacity lithium secondary battery can be manufactured using the negative electrode including the graphite composite with copper oxide.

[0240]

[Table 5]

[0241]

The negative electrode according to the present invention, that is, an electrode obtained by mixing a binder and a copper oxide-deposited graphite composite in which copper oxide is deposited on graphite capable of intercalating and deintercalating lithium has a large discharge capacity. Show. Further, since a lower potential of the negative electrode can be used, a lithium secondary battery with a high battery voltage can be provided. Therefore, an excellent lithium secondary battery can be provided using the negative electrode according to the present invention.

[Brief description of the drawings]

FIG. 1 is a diagram showing a comparison of manufacturing steps.

FIG. 2 is a diagram illustrating a relationship between a weight ratio of graphite and copper oxide and a discharge capacity.

FIG. 3 is a structural diagram of batteries manufactured in Examples 25 and 26 and Comparative Examples 17 and 18.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 positive electrode can 2 positive electrode current collector 3 positive electrode 4 negative electrode can 5 negative electrode current collector 6 negative electrode 7 separator 8 insulating packing

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kazuo Yamada 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-6-349482 (JP, A) JP-A-6-349 325753 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 4/36-4/62 H01M 4/02-4/04 H01M 10/40

Claims (5)

(57) [Claims] 1. All or all of graphite particles capable of intercalating / deintercalating lithium ions
Decompose compounds containing copper ions on some surfaces
A lithium secondary battery comprising: a negative electrode comprising a copper oxide-adhered graphite composite produced by a method for producing copper oxide produced on a surface by the method and a binder. 2. A method of producing copper oxide by a chemical reaction, comprising producing copper hydroxide by a neutralization reaction in a solution of a salt containing copper ions mixed with graphite particles, precipitating together with the graphite particles, and then dehydrating. 2. The method according to claim 1, wherein
The lithium secondary battery according to the above. 3. The secondary lithium battery according to claim 1, wherein the particle size of the graphite particles constituting the graphite composite attached to copper oxide is 80 μm or less and larger than the particle size of the generated copper oxide alone. battery. 4. The copper oxide-adhered graphite composite, wherein a ratio of copper oxide in contact with graphite is 98.5: 1.5 to 55:45 in weight ratio of graphite to copper oxide. The lithium secondary battery according to claim 1, wherein 5. The lithium secondary battery according to claim 1, wherein the weight ratio of the copper oxide-adhered graphite composite and the binder constituting the negative electrode is 99: 1 to 70:30.